Concentration of minerals by froth flotation



LOCKWOOD 'W. FEBRIS, OF SA'LTLAKE CITY, UTAH CONCENTRATION OF MINERALS IBY FROTH No Drawing.

silicate or chrysocolla, have, up to the present,

never been successfully concentrated by froth flotation methods. Some forms of copper silicate have been floated, but the recoveries have been low and the grade of the concentrate poo-r.

I have discovered that if these refractory oxidized copper ores, containing copper sllicates, are heated to a temperature sufticiently high to decompose these refractory minerals, this temperature not to exceed a dull .red heat, the minerals change color, usually from green or blue to brown and black, and when the product which has been subjected to heat is subjected to a froth flotation operation, the copper can be recovered in the form of a high gradeconcentrate, and the recovery of this hitherto rebellious copper very high.

If the ore contains, besides oxidized copper minerals, including silicates, sulphides of copper, these must first be removed before su jecting the material to the heat treatment. This heat treatment can be carried out in any of the eflicient roasting mechanisms now on the market.

The ore, it free from sulphides, can be crushed rather coarse and then subjected to the heat treatment, then cooled and ground to the required degree to free the mineral particles from the gangue particles, and the resultant fine ground material subjected to a froth flotation operation. Or, it the ore contains sulphides: of copper or sulphides of other minerala-tne ore is crushed, ground and floated in the usual manner, removing the sulphide minerals, the tailings from this operation containing the oxidized copper minerals, including copper silicates, are dried and heated to the proper temperature, and then water added to the proper pulp density and this pulp subjected to a froth flotation operation, so as to recover the oxidized copper minerals in a froth, in the usual manner.

While I do not desire to limit myself by any theoretical explanation of the exact nature of the reaction which takes place when the FLOTATION Application filed December 11, 1928. Serial No. 325,396.

copper silicates are heated, nevertheless, I be lieve the action of the copper silicates, viz., their floatability, after they have been heater 1, is due to the breaking up of the silicates of copper, so as to form copper oxides and silica, SiO and this liberated copper oxide is amenable to flotation concentration.

Having thus described my invention, what I claim is:

The method of effecting the flotation of silicate forms of copper minerals, which com-,

prises subjecting such ores and materials to heat alone in the absence of reagents, so as to decompose such copper silicates and subjecting the heated material to a froth flotation operation.

In testimony whereof, I aflix my signature.

LOCK'WOOD W. FERRIS. 

